"Exploration - What does the magnitude of frictional force have to do with" Motion and Force PPT Courseware 2

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"Exploration - What does the magnitude of frictional force have to do with" Motion and Force PPT Courseware 2

Self-study textbook answer:

1. What is sliding friction?

2. What is sliding friction?

3. What are the conditions for the generation of sliding friction?

4. What is static friction? Rolling friction?

1. When one object slides relatively on the surface of another object, a phenomenon that hinders relative sliding occurs, which is called sliding friction.

2. The force generated during sliding friction is called sliding friction.

3. The friction generated between two relatively stationary objects is called static friction.

4. The friction produced when one object rolls on another object is called rolling friction.

Friction phenomena in life:

Think about it: a football rolling on the ground or a vehicle with its engine turned off will eventually stop. Why is this?

Try it: slide your hands on the table and rub your feet on the ground. How do you feel?

Summarize:

The uneven surface of an object is one of the causes of friction.

There are many hypotheses about the generation of friction. After class, students can find relevant information through books and the Internet.

What should they do?

Question 1: Xiao Ming asked his mother to buy a bottle of canned fruit, but Xiao Ming couldn’t open the lid. Can you help him?

Question 2: Xiaohua is going to participate in the school rock climbing competition on Sunday. What do you think Xiaohua should do to prevent him from slipping and reach the finish line as soon as possible?

Question 3: Xiaohong’s mother went to the market and bought some loaches, but Xiaohong couldn’t catch them. What should she do?

1. Explore the factors that affect the magnitude of friction

1. Conjecture: What factors may be related to the magnitude of friction?

The size of the pressure, the size of the object's gravity, the size of the movement speed, the size of the contact surface, the roughness of the contact surface...

Kind tips:

1. How to measure friction?

2. What methods do you plan to use to research your chosen topic?

2. Verification plan:

(Controlled variable method: Let one factor that affects friction change, while keeping other factors unchanged, and study the relationship between friction and this external factor.)

What do you do: (please write it down)

(Note: The object must be pulled at a constant speed. The friction force can be reflected from the indication of the spring balance)

2. Methods to increase or decrease friction:

1. Harmful friction in life:

Example: wear and tear of machine parts;

Reduction method: reduce pressure and increase smoothness;

2. Helpful friction in life:

For example: the pattern of shoe soles, bicycle brake pads made of rubber;

Increase method: increase the pressure and increase the roughness of the contact surface;

Classroom test:

1. Regarding friction, which of the following statements is wrong ( )

A. The size of sliding friction is related to the pressure between objects and the roughness of the contact surface.

B. Under the same conditions, rolling friction is smaller than sliding friction

C. Friction is always harmful under any circumstances

D. There are uneven patterns on the tires to increase friction.

(2) When cyclists brake in an emergency, they press the brakes hard for the purpose of ( )

A. Increase pressure to increase friction

B. Make the contact surface rough to increase friction

C. Reduce friction

D. None of the above statements are correct

(3) Regarding the magnitude of sliding friction, which of the following statements is correct ( )

A. The larger the contact area between the two wooden blocks, the greater the sliding friction force.

B. When sliding on the same contact surface, the sliding friction force on the wooden block increases with the increase of pressure.

C. The faster the two wooden blocks slide relative to each other, the greater the sliding friction force.

D. As long as the contact surface is rough, there will be sliding friction between the two wooden blocks.

(4) Among the following kinds of friction, the harmful friction is ________, and the beneficial friction is ________.

① When the machine is running, the friction between the various parts

② Friction between hands and rope during tug-of-war competition

③Friction between the car and the air when driving

④ Friction between chopsticks and food when eating

(5) my country’s first maglev train line, which attracted the world’s attention, was built in Shanghai. Scientists use magnetic levitation to disengage the train from the guide rails in order to increase the speed of the train.

Extracurricular practical activities:

Investigate where there is friction around your life? And with "What would the world be like if there was no friction?"

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For more information about the PPT courseware "Motion and Force to Explore What the Size of Friction is Related to", please click the Motion and Force ppt to Explore What the Size of Friction is Related to ppt tag.

"Exploring - What does the magnitude of frictional force have to do with" Motion and Force PPT Courseware 5:

"Exploring what the magnitude of friction is related to" Motion and Force PPT Courseware 5 Activity 1 Place the wooden block (replacement of the car) on the table and push it to make the car move on the table. The car will eventually ________. Why? Press your palms against the table and drag slowly..

"Exploring - What does the magnitude of frictional force have to do with" Motion and Force PPT Courseware 4:

"Exploring what the magnitude of friction is related to" Motion and Force PPT Courseware 4 Friction in Life 1. Why can people glide quickly on the ice? 2. Why can people skate on cement surfaces? 3. Why do car tires often have concave and convex patterns? 4. Football...

"Exploring - What does the magnitude of frictional force have to do with" Motion and Force PPT Courseware 3:

"Exploring what the magnitude of friction is related to" Motion and Force PPT Courseware 3 Self-study textbook answers: 1. What is sliding friction? 2. What is sliding friction? 3. What are the conditions for the generation of sliding friction? 4. What is static friction? Rolling friction? ..

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Update Time: 2024-09-07

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